let hanbetsushiki a b c = b ** 2.0 -. 4.0 *. a *. c
let test1 = hanbetsushiki 1.0 5.0 4.0 = 9.0
let test2 = hanbetsushiki 2.0 (-4.0) 2.0 = 0.0
let test3 = hanbetsushiki 1.0 2.0 4.0 = -12.0
let kai_no_kosuu a b c = if hanbetsushiki a b c >= 0.0
then
if hanbetsushiki a b c = 0.0 then 1 else 2
else 0
let test1 = kai_no_kosuu 1.0 5.0 4.0 = 2
let test2 = kai_no_kosuu 2.0 (-4.0) 2.0 = 1
let test3 = kai_no_kosuu 1.0 2.0 4.0 = 0
let kyosuukai a b c = if kai_no_kosuu a b c > 0 then false else true
let test1 = kyosuukai 1.0 5.0 4.0 = false
let test2 = kyosuukai 2.0 (-4.0) 2.0 = false
let test3 = kyosuukai 1.0 2.0 4.0 = true